Feedlots promote animal growth and improve the quality of the animal prior to slaughter. Although some feedlots are designed to handle relatively few cattle, most of the feedlots in North America are considerably larger and accommodate thousands of animals. There is considerable diversity in individual animal characteristics, such as weight, frame size, fat content, fat deposition rate, intramuscular fat (marbling) and muscling within this feedlot cattle population. The producer's goal in using a feedlot is to optimize the growth rate and food value characteristics of each animal prior to slaughter. Achieving this goal ideally requires obtaining physical data and growth characteristics for each animal at multiple times during its stay in the feedlot.
Some of these measurements have been made using probe-like instruments. For instance, backfat has been measured by piercing the skin of the animal and taking physical measurements. This clearly aggravates the animal and may be illegal in certain areas. See Carlson's U.S. Pat. Nos. 4,359,055 and 4,359,056. Ultrasound techniques have been developed to replace these physically invasive and time-consuming methods. Ultrasonic devices transmit ultrasonic waves into the animal. Ultrasonic waves are transmitted and reflected by muscle tissue differently than by fat. As a result, the reflection of ultrasonic waves can determine certain meat characteristics, including the depth of various fat layers by determining fat boundaries or fat/tissue boundaries.
The meat producing industry has tried to use ultrasound devices for years to efficiently measure internal tissue characteristics. See, for instance, Carlson's patents which describe an ultrasonic digital backfat meter that was designed primarily for use with swine. Known devices have proven inefficient for monitoring large numbers of cattle. Measuring each animal takes too much time, and often the results are inaccurate. The speed of the measurement depends on several factors. For instance, cattle have relatively thick hair compared to other food producing animals, such as swine, which decreases ultrasonic conductivity. In order to obtain an acceptable signal, operators often clip the cattle's hair close to the skin before the ultrasound device is placed in contact therewith. This takes time and is impractical for feedlots in which many hundreds or thousands of animals must be measured, sometimes more than once, during their residency in the feedlot. When a proper conductive contact between the device and the animal is not achieved, a poor image of internal fat and muscle tissues is obtained. It is not possible to accurately measure tissue dimension or texture characteristics under such conditions.
Operators have tried spraying a conductive liquid onto the animal using a squirt bottle immediately prior to placing ultrasonic devices in contact with the animal so as to eliminate the need for hair clipping. This also has proven ineffective for large feed lots. Manipulating both the ultrasound device and the squirt bottle is inconvenient, and the time required to apply the liquid adds significantly to the processing time.
Another drawback associated with known devices is that the controls are not integrated at the fingertips of a single operator. More than one operator may be required to operate the device. Alternatively, a single operator may have to reset and reposition the ultrasound device after each animal is tested by moving to a location remote from the testing site where the computer is located. As a result, known ultrasonic techniques take as long as 120 seconds to measure each animal. While this may not seem like a significant amount of time, it is considerably too long when thousands of animals must be processed daily.